The sprouting of needle-like, pointed and hard leaves on a juniper that normally has a scale-like and soft foliage is a defense mechanism of the plant.
In the wild, some animals feed on the soft leaves especially of young juniper plants. The plants then feel threatened and are stressed. As a result, the plants develop a pointed and hard foliage in the gnawed areas to counteract the wild browsing in this way.
One could compare this behavior with that of the hedgehog, which curls up in danger and shows only its pointed spines to predators.
This behavior can be observed in various juniper species, such as the Chinese Itoigawa juniper (Juniperus chinensis shimpaku var. itoigawa) or the Phoenician juniper (Juniperus phoenicea). To avoid the sprouting of hard tips, especially young plants should not be pruned in the first 2 years.
However, even in already older plants, this defense mechanism can sometimes be observed when they are heavily pruned back. It is therefore advisable to carry out smaller partial pruning more often than annual heavy pruning. The plants should be observed after each pruning and the pruning should be adapted to the behavior of the plants.